In a large cast iron pot (with a lid), cook the bacon on medium heat with the bay leaf and thyme sprigs. Once bacon has become crispy, remove from the pan so it doesn't burn. Drain all but about 4tbsp of the bacon grease.
With the pan still on medium heat, add the onion and sweat, stirring frequently. Once the onion begins to caramelize, add the chopped mushrooms and Brussels sprouts, season with salt and pepper and toss together. Sauté for 5 minutes or so.
Add the chicken stock/broth, reduce heat and cover for 10 minutes, stirring every few minutes as it cooks. Serve topped with sliced pork tenderloin, seared salmon, or any of your favorite proteins.